so we went defensive spreading the water from the top of our ladder pipe in from the outside into the windows. that's what we call a defensive fire. >> reporter: when you're looking for hot spots, there's a lot of voids you say that hot spots could be hiding. >> with the collapse of the structure, the second floor, it's creating void spots that we can't get to the fire. so there's small hidden hotspots that we're trying to get to. we'll be here all morning waiting for daylight to break so we can evaluate the structure and how far we can get in. >> reporter: all right, deputy chief gil dong, thank you for that. again, the investigation continuing. there was some talk that the firefighters might be looking at a propane tank as part of the cause. but that's not being confirmed at this point. they are look at everything and the investigation will continue later on this morning. also want to give some props to the berkeley pd because they were able to help a woman in a wheelchair out of the home. no injuries for firefighters or residents. also, should mention that some of the surrounding h